The old activity filled a jar with dishwasher detergent or trisodium phosphate and claimed the layers would reveal organic matter. We have retired that method. Those chemicals are unnecessary for a children's observation, and a home settling jar cannot replace a laboratory nutrient, contaminant, or organic-matter test.
Try a Texture-by-Feel Observation
- Ask an adult for a small sample from an ordinary garden area, avoiding places that may contain animal waste, broken glass, treated-wood residue, or chemical spills.
- Remove stones and roots. Moisten a spoonful gradually with clean water until it feels like soft putty, not dripping mud.
- Rub a pinch between finger and thumb. Sand feels gritty. Silt feels smooth or floury. Clay feels sticky and can form a ribbon when gently pressed forward.
- Try to form a ball, then a thin ribbon over a finger. How long it holds together gives a clue about clay content.
- Record what you feel in the Garden Journal, wash your hands, and remember that this is an estimate.
Get a Laboratory Test
A laboratory test is the best way to learn pH, organic matter, and nutrient levels and receive amendment recommendations. Ask a local university extension service, provincial agriculture office, or accredited soil laboratory how to collect a representative sample. Their instructions specify depth, number of subsamples, container, and information about the planned crop.
Do not test only the “best-looking” handful. A useful sample combines small amounts from several spots in the same garden area. Test a visibly different soil or a place with a different history separately.